Views on when to/not to allow a dog to be social

Thanks, all. In some ways I still feel it's a little contradictory but I understand the parameters give. Big test today-we are taking him to the nature preserve near us for a walk. I am working on leash training but I'll be the first to say it's not going that great LOL! Probably fine for a 14 week old puppy but he needs lots of work. There will be people, other dogs, maybe horses and lots of smells. Add a pokey old springer to the mix and it should be lots of fun!